1. Field of the invention
The present invention pertains to a slide flute type of musical instrument, and, in particular, the present invention pertains to such an instrument with a wide octave range and fine control of the dynamic characteristics.
2. Background Information
Musical wind instruments fall into two major categories, namely open pipes and closed pipes. Open pipe musical instruments are resonant columns of air enclosed in a pipe with openings at both ends. Closed pipe instruments are resonant columns of air enclosed in a pipe with an opening at one end and sealed (i.e. “closed”) at the other. The excitation to set either kinds of pipes into their resonant modes of vibration comes from one the following sources: i) a vibrating reed attached to the closed end, such as in the clarinet; ii) vibrating lips of the player, also called the “lip-reed”, such as in the trombone and trumpet; and iii) simply “air reed”, where a player blows a jet of air on to an edge of some sort at one end of the pipe. The flute and the recorder are common examples of “air reed” musical wind instruments.
The flute and recorder families are some of the most widely played open pipe instruments. In the case of the flute, the air jet is blown across the embouchure hole (or blow hole) towards its far edge. In the recorder, the jet is channeled toward an edge via a fipple. Clarinets, oboes, saxophones, and bassoons are closed pipe reed instruments, while brass instruments like trombones and trumpets are closed pipe “lip reed” instruments. The slide whistle, while classified as a toy, is also a closed pipe instrument (it is always closed at the piston end; the excitation comes from a recorder-like fipple at the other end).
The flute derives its open pipe characteristics from the fact that it is always open at the blow hole at one end while the other open end is either the first open tone hole, if any, or the open end of the pipe. The flute is excited into its resonant modes by the player blowing a rapid jet of air across the blow hole, which has a properly angled edge on the opposite side. The edge splits the air into two streams one of which escapes into the surrounding atmosphere while the other creates rotating eddies at the mouth of the blow hole. The rotating eddies in turn create acoustic pressure waves that are propagated along the length of the pipe. The angular velocity of the rotating eddies is a complex function of the blowing and the position of the player's lips with respect to the blow hole. When a critical angular velocity is reached that corresponds to the resonant frequency of the pipe for any given length, the pipe is spontaneously set into its resonant mode of vibration.
The pitch of the resonant mode of the flute is inversely related to the length of the vibrating air column. In a first approximation of flute theory of operation, the effective length of the vibrating air column is the distance from the blow hole to the first open tone hole. Thus by opening successive tone holes at greater distances from the blow hole, while keeping all other tone holes closed, the pitch of the fundamental resonant mode can be reduced in steps.
The operation of the slide whistle, variously also known as a swanee or swannee whistle, piston flute or jazz flute, is well known. It is a closed pipe instrument whose body consists of a cylindrical pipe, at one end of which is attached a recorder-like fipple for a mouthpiece. In some designs, the mouthpiece is flute-like, with a blow hole. The other end of the pipe is closed and air sealed by a movable piston that can slide up and down the length of the pipe. The position of the piston along the length of the pipe determines the length of the air column enclosed in the pipe. The pitch of the sound produced, as in all pipe instruments, is inversely proportional to the length of the air column.
In view of the ability to move the piston in a continuous manner thereby varying the length of the air column in a continuous manner, the slide whistle, in theory, provides continuously variable pitch control. However, during the actual playing of such an instrument by virtue of moving the piston up and down the pipe, the closed pipe causes conflicting air flow patterns and pressure variations at the mouthpiece, which provides the only inlet as well as outlet for the enclosed air, leading to unintended and random overtone generation and other pitch variations. Hence the sound produced by this instrument is often a medley of tones and pitches, quite unsuitable to play serious music and, hence, it is classified as a toy. Quite apart from these limitations, the inherently sluggish movement of a piston type of arrangement does not lend itself to fine dynamic control.
U.S. Pat. No. 4,320,686 discloses an open pipe wind instrument with a continuously variable pitch control, hereinafter referred to as slide flute. The relevant features of this instrument include: a pipe with a slot running along some part of its length; and a method to selectively cover the slot up to any point along its length. In one embodiment, the method used to seal the slot up to any point along its length is accomplished by means a flexible or pliable strip of material attached to the body of the flute. The user must run a finger back and forth over the strip and press it down at the desired point on the slot covering it up to that point. The instrument disclosed this patent, while providing a practical viable flute design, is inadequate in providing the required dynamic performance and control as well as air seal. This inadequacy persists regardless of the type of flexible strip used, for example a flexible magnetic strip or a thin strip of bendable wood. As a result, sliding or continuous pitch flutes of this kind neither consistently produce the desired pitch nor allow for the desired fine dynamic control and hence are musically unviable.
Additional prior art of interest includes U.S. Pat. No. 2,806,399 that discloses a wind musical instrument with a “helical frequency determining means” wherein a cooperating member is rotated relative to the resonating pipe to vary the effective pipe length. This rotational design is not considered to practically yield the desired control or sound quality needed in the art. U.S. Pat. Nos. 2,544,033; 2,575,540; 3,202,031; 3,599,256; 4,401,007; 5,808,218; and U.S. Publication 2002-0178892 also disclose teachings regarding wind instrument construction that are helpful in understanding the general scope content and knowledge of the prior art. All of the above mentioned patents are incorporated herein by reference.
It is an object of the present invention to overcome the deficiencies of the prior art and a provide slide flute type of musical instrument, both of the closed-pipe slide whistle/flute design and of the open-pipe design, with a wide octave range and fine control of the dynamic characteristics.